Dock levelers are used to bridge the gap between a vehicle (e.g., a truck or a trailer) and a loading dock at which the vehicle is parked for unloading or loading. Dock levelers include pit-type dock levelers, which are mounted within a pit in the loading dock, and edge-of-dock levelers, which are mounted on the front edge of the loading dock.
Prior art edge-of-dock levelers include manual levelers wherein an operator uses a lever to raise the edge-of-dock leveler above the level of a vehicle bed parked adjacent to the dock. The leveler is then lowered and a lip extends to engage the vehicle bed. These edge-of-dock levelers commonly include a spring that biases the edge-of-dock leveler upwardly to assist the operator when raising the leveler.
Other prior art edge-of-dock levelers include powered levelers. For example, one type of powered edge-of-dock leveler utilizes a hydraulic actuator to raise and lower the leveler. Another type of edge-of-dock leveler includes a fan or blower and an air bag. The air bag is inflated with the blower, raising the edge-of-dock leveler through a linkage. Examples of powered edge-of-dock levelers utilizing a blower and air bag are disclosed in U.S. Pat. Nos. 5,450,643 and 5,621,938.